1. Field of the Invention
This invention relates to a treadmill, more particularly to a treadmill which is foldable and which can be raised to an inclined position.
2. Description of the Related Art
FIGS. 1 and 2 show a conventional treadmill which includes a support frame 1, an instrument panel 2, a tread base 3, a front leg frame 4, a linear actuator 5 and two hydraulic lifting units 6. The support frame 1 includes two slide rails 101. The instrument panel 2 is mounted on the support frame 1. The front end of the tread base 3 has two mounting arms 301 connected pivotally to the support frame 1. The front leg frame 4 has upper ends connected pivotally to the tread base 3 and lower ends provided with wheels 401 which are disposed slidably in the respective slide rails 101. The linear actuator 5 is mounted on the bottom of the tread base 3 and includes a screw rod 502 driven by a motor 501 and a threaded sleeve 503 connected telescopically to the screw rod 502 and connected pivotally to the front leg frame 4. Each hydraulic lifting unit 6 has a front hydraulic cylinder 601 mounted pivotally on the support frame 1 and a rear piston rod 602 connected pivotally to the tread base 3.
When the tread base 3 is to be raised to an inclining position for the user to exercise thereon, the screw rod 502 of the linear actuator 5 is rotated by the motor 501 to retract the threaded sleeve 503. The front leg frame 4 is thus pulled and the wheels 401 are moved along the slide rails 101 so that the mounting arms 301 are inclined and the tread base 3 are raised by the front leg frame 4.
Referring to FIG. 3, when the tread base 3 is to be folded for storage, the linear actuator 5 is first operated to extend forward the threaded sleeve 503 so as to place the tread base 3 in a horizontal position. Then, the tread base 3 is lifted upward manually so that the hydraulic lifting unit 6 is extended and turned upward together with the tread base 3. At this juncture, a spring latch 302 provided on the tread base 3 is automatically moved into a latch hole 201 of the instrument panel 2, thereby positioning the tread base 3. The tread base 3 is further stabilized in its folded upward position by the hydraulic lifting unit 6.
However, the conventional treadmill has a disadvantage in that the construction thereof is rather complicated and that the spring latch 302 is unsafe as it can drop from the latch hole 201 due to vibration. In addition, when the tread base 3 is to be unfolded for use, the user must pull out the spring latch 302 from the latch hole 201 with one hand while holding the tread base 3 with another hand to prevent the tread base 3 from falling down accidentally. The need to pull out the spring latch 302 is therefore troublesome.